Re: [linux-stable-rc:queue/5.4 4610/23441] include/linux/compiler.h:350:45: error: call to '__compiletime_assert_215' declared with attribute error: FIELD_GET: mask is not constant

[Vegard Nossum <vegard.nossum@oracle.com>]

On 5/23/23 15:37, Vegard Nossum wrote:
> 
> On 5/21/23 02:12, kernel test robot wrote:
>> Hi Vegard,
>>
>> FYI, the error/warning still remains.
>>
>> tree:   
>> https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git queue/5.4
>> head:   9b5924fbde0d84c8b30d7ee297a08ca441a760de
>> commit: 3910babeac1ab031f4e178042cbd1af9a9a0ec51 [4610/23441] 
>> compiler.h: fix error in BUILD_BUG_ON() reporting
>> config: sparc64-randconfig-c44-20230521
>> compiler: sparc64-linux-gcc (GCC) 12.1.0
[...]

> I'm not sure why this flags my patch as the culprit.
> 
> I just tried this (with the supplied config):
> 
> git checkout stable/linux-5.4.y
> git revert 3910babeac1ab031f4e178042cbd1af9a9a0ec51 # revert my patch
> make drivers/net/wireless/mediatek/mt76/mt7615/mac.o
> 
> and it still outputs the same error.
> 
> The FIELD_GET() call was added in bf92e76851009 and seems to have been
> broken from the start as far as I can tell? If I checkout bf92e76851009^
> then it builds, if I checkout bf92e76851009 then it fails.
> 
> Should we just redefine to_rssi() as a macro so it actually passes the
> field as a literal/constant?

Ah, there is a mainline patch that fixes this, doing exactly that:

commit f53300fdaa84dc02f96ab9446b5bac4d20016c43
Author: Pablo Greco <pgreco@centosproject.org>
Date:   Sun Dec 1 15:17:10 2019 -0300

     mt76: mt7615: Fix build with older compilers
[...]

-static inline s8 to_rssi(u32 field, u32 rxv)
-{
-       return (FIELD_GET(field, rxv) - 220) / 2;
-}
+#define to_rssi(field, rxv)            ((FIELD_GET(field, rxv) - 220) / 2)

Greg, Sasha, does it make sense to pick that for 5.4 (as it doesn't seem
to be in there) to shut up the kernel test robot?

If so, should we add this to the changelog as well?

 >> If you fix the issue, kindly add following tag where applicable
 >> | Reported-by: kernel test robot <lkp@intel.com>
 >> | Closes:
 >> 
https://lore.kernel.org/oe-kbuild-all/202305210701.TND2uZBJ-lkp@intel.com/
 >>


Vegard